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Site Details

© Copyright and database right 2019. All rights reserved. Ordnance Survey licence number 0100022206

NPRN 95309

Map Reference SH45NW

Grid Reference SH43705635

Unitary (Local) Authority Gwynedd

Old County Caernarfonshire

Community Llandwrog

Type of Site HILLFORT

Broad Class DEFENCE

Period Iron Age

Site Description 1. Dinas Dinlle hillfort is a roughly oval defended enclosure, set on the summit of a drumlin. It measures about 150m north-south by 110m and is defined by double ramparts with an intermediate ditch; there is an entrance in the south east. The enclosure has suffered considerable coastal erosion on the west side and from the beach below, the original ground surface beneath the Iron Age ramparts along with other details are clearly visible in the eroded cross-section. Within the eastern part of the interior are traces of circular or rectangular structures or enclosures, one being a possible sepulchral mound or alternatively a Roman pharos or lighthouse, or a defensive watchtower, similar to one to the north on Caer y Twr, Holyhead Mountain (nprn 308080).
Casual finds, including Roman coins of A.D. 253 to 296, an intaglio and a sherd of black burnished ware of the second or third centuries, indicate occupation in the Roman period.
A World War Two Seagull Trench (nprn 270526) has been built in the lower north-facing ramparts of the fort.
RCAHMW, 12 July 2009.

2. The site is on a 30m high hill of glacial drift on the western edge of the Caernarfonshire coastal plain. This natural hill has been adapted and reinforced in the typical style of an Iron Age Hillfort with defensive central area surrounded by banks and ditches. The fortifications survive on three sides only today, the west side has been eroded away possibly during the last 100 years or so by the sea. Formerly the site may well have stood well inland. Alternatively the glacial hill may have been a coastal prominence with sea on three sides. It has a history in that it has been commented on as a site since at least the mid C18th and there are a number of references to it as a “Camp” in the mid C19th notably in Arch Camb 1846 where there is also a fine illustration of the site from the east. It is a lone survival in the area and there are no other Hillforts nearby given the topography any scope to build one. The Hillfort on the summit of Garn Boduan is possibly the nearest similar site. It is a fine survivor but is very seriously threatened by sea erosion. This erosion has continued and has been noted for some time and its progress has been plotted from available data. It will no doubt be accentuated by sea level rise / climate change but he main threat is simply wave and wind action at present. The site exhibits not only fine surviving defences but also due to the sea erosion and a deep layer of wind blown sand some of its archaeological horizons. From the result of footpath and animal erosion some detail of its construction and its entrance features have been revealed. The volatile state of its preservation presents opportunities for archaeological investigation and better understanding of the site. The interior has possibly some buried and surviving features revealed by geophysics and there are opportunities also for further investigation and “test-pitting”. There are several notable finds from the site including pottery coarse wares of the mid C3rd AD and coins from the same period, possibly indicating re-use during the Roman occupation.
John Latham RCAHMW 1 November 2016

3. In 2017 the hillfort became the focus of new archaeological and palynological research and survey work as part of the 2017-2021 EU-funded CHERISH Ireland-Wales project. The eroded hillfort was selected as a study site and in 2017-18 saw new geophysical survey carried out by the Gwynedd Archaeological Trust, and new topographic (GNSS), laser and photogrammetric survey by the Royal Commission. Survey work has extended to encompass the southern slopes beyond the hillfort defences where the geophysical survey identified the remains of historic farms depicted on the Tithe Award Survey, but also earlier traces of probable prehistoric fields and boundaries.

T. Driver, L. Barker, D. Hunt, RCAHMW for the CHERISH Project, 2018.

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